Electric arc welding is well known, and is performed with a variety of processes using a variety of types of equipment. One electric arc welding process is a pulse spray process, which is typically performed using a wirefeeder and a power supply. An example of a prior art power supply used in pulse spray welding is a Miller S64M.TM. wirefeeder. The Miller S64M.TM. wirefeeder may be used with a Miller XMT304.TM. power supply.
Typically, in pulse spray processes, power is provided from the power supply to the wirefeeder, and the wirefeeder provides the wire and power to the arc. The wirefeeder typically includes a controller, which may be part of or separate from the wirefeeder, and which controls the wire feed speed based on a user-selected input. Additionally, the controller provides a command signal to the power supply which causes the power supply to output a current and voltage at a desired magnitude. The command is produced in response to a user-selected wire feed speed. The power supply provides a specified current by adjusting the output voltage until the desired current is obtained. The current amplitude is often controlled as a function of time, switching between a background current and a peak current, thus creating a pulsed output.
The welding process is often controlled by controlling various welding parameters. For example, the pulse spray process is typically controlled by adjusting such welding parameters as A) peak amps, B) background amps, C) pulse width, and D) frequency. The parameters are typically adjusted using a controller which provides control signals to the wire feeder (or power supply). As used herein, welding parameters refer to parameters of the welding power output, such as peak amps, background amps, frequency, and pulse width.
Some wirefeeder controllers include factory programs which preset various welding parameters. The values for these parameters are stored by the controller (often in digital or other types of memory). Also, many controllers allow the user to store user-created programs which store user-selected welding parameters. In such a case, the user teaches or sets the desired values for welding parameters, and stores them in the memory.
When the user wishes to access either the factory preset or the user-created programs, they are individually selected using some type of digital interface. Then, the controller commands the power supply to provide power at the called for current, peak current, background current, frequency and pulse width, thus providing the desired welding parameters.
Different types of welding require different types of arc characteristics (such as the plasma cone angle.backslash.width and intensity, hereafter referred to as arc width). For example, flat, horizontal down, welding typically may be performed using a relatively wide arc. Conversely, overhead welding, or welding in other difficult or inconvenient physical positions, often requires a narrow arc.
The preset factory programs are typically set to provide for welding with a wide arc, since this is the one most inexperienced welders will use. To access the narrower arc the welder must adjust the welding parameters manually and individually until the desired arc is obtained. It may be necessary to decrease one parameter as another parameter is increased, so that arc characteristics such as arc length do not change. Power and/or deposition rate do not change in alternative embodiments.
However, many welders lack the experience to know how to properly adjust the various parameters, and in particular welders do not understand the interaction between adjusting various parameters For example, to decrease arc width, frequency is decreased. However, increasing frequency also increases arc length. Many welders do not know this, nor do they know how to adjust the other welding parameters to offset the effect of changing frequency on arc length.
Some prior art wirefeeders provide for automatic adjustment of two welding parameters. The Miller 60M.TM. wire feeder includes a trim setting that adjusts up to two parameters (frequency and/or peak amps). Other welding power supplies may also adjust two welding parameters with a single knob. However, these do not properly adjust the arc width to a desired value while maintaining one or more other arc characteristics constant by adjusting welding parameters.
Accordingly, it is desirable that a welding power supply and wirefeeder include a controller that allows the user to adjust the arc width using a single knob, such that multiple welding parameters are adjusted to obtain a desired arc width, while maintaining one or more other characteristics of the arc.